水力发电学报
            首 页   |   期刊介绍   |   编委会   |   投稿须知   |   下载中心   |   联系我们   |   学术规范   |   编辑部公告   |   English

水力发电学报

• 当期目录 • 上一篇    下一篇

堆积体对近床面水流紊动强度试验研究

  

  • 出版日期:2018-04-25 发布日期:2018-04-25

Experimental study on turbulent intensity of near-bed flows in rivers affected by deposit

  • Online:2018-04-25 Published:2018-04-25

摘要: 采用声学多普勒流速仪ADV对概化水槽中受堆积体影响河道的流速进行了精细的测量,并将数据代入无量纲化的紊动强度计算公式来分析流量、河道缩窄率、堆积体侧向坡度对河道近床面紊动强度分布的影响。试验结果表明:以堆积体对称轴断面为起点,在下游相对距离0 ~ 1.5断面处,由于堆积体对水流的束窄和突扩作用导致出现水跃,紊动强度波动较大形成强紊动区,且随阻流作用的增加而增加;在相对距离1.5 ~ 4.5断面,由于水流持续扩散导致紊动强度衰减,但左岸受回流影响紊动强度衰减较缓,因此左岸变化率小于右岸,且变化率随阻流作用的增加而增加;在相对距离4.5 ~ 6.5断面,紊动强度逐渐恢复平稳状态且大于相对距离-4.5 ~ 0断面。试验结论揭示了河道中的水流紊动特性及堆积体对河道水流紊动影响的内在机理,加深了对堆积体作用下的水流运动、泥沙冲淤和输移规律及河床演变发展变化的认识,可为研究山区河流受堆积体影响的河道水流紊动特性的数值模拟提供验证资料。

Abstract: In this laboratory flume experiment, an acoustic Doppler flow meter ADV is used to measure flow velocity in a generalized channel that is affected by a sediment deposit body, and the measured data along with a formula for calculation of dimensionless turbulent intensity are used to analyze the influence of flow rate, river narrowing rate, and deposit lateral slope on the distribution of near-bed turbulent intensity. Results show that under the effect of narrowing and sudden expansion of the flow around the deposit body, a hydraulic jump occurs in a downstream section of relative distance 0.0-1.5 (ratio of distance over channel width) from the centerplane of the deposit, characterized by large fluctuations in turbulent intensity and a region of strong turbulences that are strengthened by the deposit blocking effect. In relative distance of 1.5-4.5, further expansion of the flow reduces turbulent intensity at a rate that increases with the blocking effect. And this reduction takes a lower rate near the left wall than that near the right wall due to the affect of a wake zone at the right side. In relative distance of 4.5-6.5, the mean flow is gradually recover to a steady state but with its turbulent level higher than that of the inflow in the relative distance of -4.5-0.0. This experiment reveals the inherent mechanism of turbulences developing in rivers and the influence of the deposit, shedding light on the flow and sediment transport around a deposit body and the related scour and sedimentation process and bed evolution. It also provides measured data for verification of the numerical simulations of turbulent characteristics of the flows in mountain rivers.

京ICP备13015787号-3
版权所有 © 2013《水力发电学报》编辑部
编辑部地址:中国北京清华大学水电工程系 邮政编码:100084 电话:010-62783813
本系统由北京玛格泰克科技发展有限公司设计开发  技术支持:support@magtech.com.cn